breakfast.clj

(defmethod menu :breakfast
  [_]
  ["scrambled eggs"
   "french toast"
   "full english"])

dinner.clj

(defmethod menu :dinner
  [_]
  ["lamb shank"
   "veg lasagne"
   "pumpkin pie"])

lunch.clj

(defmethod menu :lunch
  [_]
  ["shepherd's pie"
   "bangers and mash"
   "spaghetti puttanesca"])

menu.clj

(ns menu)

(defmulti menu (fn [meal-time] meal-time))

(load-file "breakfast.clj")
(load-file "lunch.clj")
(load-file "dinner.clj")

(pr (menu :breakfast))
(println)
(pr (menu :lunch))
(println)
(pr (menu :dinner))
(println)

;; execute:
;;
;;   $ clj menu.clj
;;
;; expect output:
;;
;;   ["scrambled eggs" "french toast" "full english"]
;;   ["shepherd's pie" "bangers and mash" "spaghetti puttanesca"]
;;   ["lamb shank" "veg lasagne" "pumpkin pie"]